This invention relates to a photoelectric switch.
A variety of photoelectric switches, namely photoelectric detectors, are known that utilize a light source element, such as a light-emitting diode, and a light responsive element, such as a photoelectric transistor, for detecting the presence or absence of an article in the light path between said two elements. Such two elements are securely accommodated in a common housing or each of them is housed in an independent housing and in each case, the housing is generally made of metal or opaque plastic material and has a window means made of a glass or plastic material which is transparent to light.
Such prior art switches are, however, complex in construction and, therefore, expensive to fabricate.
It should be understood that the term "photoelectric switch" is used herein to refer not only to a device comprising both a light source element and a light responsive element in a common housing but also to a device including either a light source element or a light responsive element in a housing. Similarly, the term "light" is used herein to refer to any radiant electromagnetic energy within the far infrared to ultraviolet regions of the spectrum, including, but not limited to, visible light.
It is an object of this invention to provide a photoelectric switch which is compact, simple in construction and easy to fabricate at low cost.
Another object of this invention is to provide a photoelectric switch wherein circuit elements are housed in a fluid-tight enclosure.
A further object of this invention is to provide a photoelectric switch comprising an adjusting means for adjusting its operation characteristics.